The death toll reportedly rose to 39.
"We are trying to cut the big pieces of concrete that fell off the bridge, after which we will move them with the cranes and send in search dogs".
Atlantia has lost a quarter of its market value in the first trading since the government said it would take steps to revoke the concession to run half of the nation's toll highways following the deadly bridge collapse in Genoa.
It called for a comprehensive plan to fix or replace tens of thousands of Italian bridges and viaducts built in the 1950s and 1960s, during the Italian economy's rapid growth as the nation surged back after the damage of the Second World War.
Some witnesses claim a lightning bolt hit the bridge, causing the collapse, Ansa reported.
"This junta mustn't think that the realisation of public works isn't their problem", he said in an interview with the Genoan newspaper Il Secolo XIX.
The 1967 bridge, considered innovative in its time for its use of concrete around its cables, was long due for an upgrade, especially since the structure was more heavily trafficked than its designers had envisioned.
In 2016, structural engineer Antonio Brencich spoke of "errors in this bridge".
The motorway operator said work to shore up the bridge's foundation was being carried out at the time.
Rescuers continue their search for possible survivors and bodies of victims of Tuesday's highway bridge collapse in Italy. Conte said: "we can not wait for justice" and that "all citizens must travel in safety".
Italy's transport minister has now called on senior managers at the company which operated the motorway bridge to resign.
The tragedy has focused anger on the structural problems that have dogged the decades old Morandi bridge and the private sector firm Autostrade per l'Italia, which is now in charge of operating and maintaining swathes of the country's motorways.
Transport Minister Danilo Toninelli described the collapse as "what seems like an huge tragedy".
A French lawyer identified only as Leonine by Francetvinfo told the broadcaster that she and her husband and 3-year-old son were just entering the bridge when "we saw the pylon go completely to the right, and we realized what was happening".
Mr Toninelli said anybody found to be responsible for the tragedy would "have to pay", a sentiment echoed by other members of the government.
Among the dozens dead were three children, while a handful of survivors - some heard screaming in desperation - were pulled from the rubble yesterday.
Conte declared a state of emergency for the northern port city of Genoa for 12-months and earmarked $5.6 million from national emergency funds for removal of the remaining parts of the bridge and re-developing the road system.
Experts have previously warned the bridge was a danger.
"We can keep going for another 48 hours in the hope of still being able to find someone", said Pietro Cosola, technical director overseeing the removal of rubble.